Dr. Ray Stantz may be considered the heart of the Ghostbusters, but he’ll always be remembered for unintentionally choosing the form that Gozer the Gozerian manifested as in the 1984 film. Although the Ghostbusters would face Gozer as the Stay Puft Marshmallow Man more than once in television and comics, Gozer’s servant Idulnas later revealed to Ray that the other Ghostbusters weren't actually successful in clearing their minds of potential forms, and that his thoughts were chosen for another reason.
After supposedly neutralizing Gozer with their proton streams on top of 550 Central Park West, the Ghostbusters wanted to celebrate, but they quickly learned the infamous Traveler was still present and requested a new form to wield against them in battle. Despite Peter Venkman trying to persuade the group to clear their minds, Gozer announced a form had been chosen. The Ghostbusters learned Ray’s stray thought involving his childhood was now walking through the city, ready to begin the end of the world. Despite considerable property destruction, the Ghostbusters were able to defeat Gozer, raining hot marshmallow down on the people below.
In the IDW Ghostbusters series by Erik Burnham and Dan Schoening, the Ghostbusters are experiencing a noticeable spike in supernatural activity throughout the city. They learn that this surge is linked yet again to Gozer, specifically thanks to a terrifying entity called Idulnas. This servant of Gozer kidnaps Ray and returns him to the top of Central Park West, where he announces his plan to use Ray to choose a new form for Gozer. He reveals to his hostage in Ghostbusters #3 that the other Ghostbusters were not successful in keeping their minds blank, stating that Gozer could have manifested as “an abstract equation, a marine corps drill instructor, or... Miss February.”
Ray Didn't Decide Gozer's Form by Chance
Idulnas clarifies that Ray’s unique reception to the supernatural made him the ideal person to choose Gozer’s new form, referring to him as "the Selector." This statement proves that it was not a failure on Ray’s end, as none of the Ghostbusters were able to actually clear their minds. It also explains why Ray was also chosen as the form Vigo the Carpathian possessed in Ghostbusters 2, as his exclusive status made him an ideal target for other powerful supernatural entities. It was much to Gozer and others’ chagrin that Ray chose a form whose primary offense was its size, the form allowing the Ghostbusters to hand Gozer its first real defeat in centuries, if not ever.
Despite the other Ghostbusters' interference and Ildunas’ threats, Ray had been forewarned thanks to a special spirit guide and when the time came for him to choose again, he made sure that Gozer reutnred as the Stay Puft Marshmallow Man once again. Ildunas failed and swore revenge as he disappeared, while the victorious Ghostbusters had to yet again take down the vengeful Gozer, leaving behind another gooey blast radius for the City of New York to deal with.